Lecture 6 P2

Question 1

What is pE?

Answer 1

Is the negative base 10 logarithm of the activity of electrons in water and the extent to which natural waters are chemically reducing or oxidizing in nature

Question 2

What do low pE values signify?

Answer 2

That electrons are readily available from substances dissolved in water, so the medium is very reducing in nature.

Question 3

What do high PE values signify?

Answer 3

That the dominant dissolved substances are oxidizing agents so that few electrons are available for reduction purposes

Question 4

In natural waters what happens with redox reactions? What does that do for their counterparts?

Answer 4

In natural waters one or another redox equilibrium rxn is dominant and it determines the electron availability for the other redox rxns that occur simultaneously

Question 5

What is the pE-pH diagram for FE species?

Answer 5

The stability and distribution of chemical species in water at equilibrium are governed by pe and pH, at pE values higher than the upper dashed lien water will oxidize and pe values lower then the lower dashed water will reduce